Re: TURN-OFF downloaded apps like the built in ones?

On an unrooted device, you can only uninstall downloaded apps. If you're rooted, I you can use an app like Titanium Backup to freeze apps, which is similar to disabling. You might be able to freeze downloaded apps with it, but I don't have direct experience with it.

Re: TURN-OFF downloaded apps like the built in ones?

Well, you only need to root if you want to freeze/disable system apps that you normally can't--there aren't that many, and the ones you normally can't disable are probably protected for a good reason (except for some annoying carrier apps like Verizon's Backup Assistant Plus). And there usually isn't much need to disable an app you downloaded, because one would expect you to simply uninstall it (and then reinstall it if you want it back). What you're asking for is relatively uncommon, but at least rooting is pretty easy to do, and does give you that option.

Re: TURN-OFF downloaded apps like the built in ones?

Thanks. I ended up just uninstalling skype, instagram and some other apps, along with many other setting changes in an effort get back to the awesome battery life I enjoyed with my Note 3 when I first got it a few months ago, and before upgrading to kitkat.

If it's not those apps, yes, I can install and reconfigure the apps, logging in and setting preferences. It would be need if native android for non-rooters could do it just like for pre-installed apps.